Multipart/mixed content-type support

[raif-s-naffah]

hi there,

i'm trying to implement some IEEE standard REST API that mandates handling PUT and POST requests w/ multipart/mixed content type.

my tests w/ Rocket 5.1 so far indicate that using a Form like this one...

use rocket::FromForm;

#[derive(Debug, FromForm)]
struct OneStatement<'r> {
    doc: &'r str,
    files: Option<Vec<TempFile<'r>>>,
}

in a handler such as ...

#[put("/", data = "<form>")]
async fn put(mut form: Form<OneStatement<'_>>) -> MyResponse {}

fail w/ 415 (Unsupported Media Type) presumably b/c Rocket doesn't recognize the multipart/mixed content-type header and consequently doesn't route the Request to the handler.

q1/ is there already some Rocket feature that makes this possible?

one alternative would be to handle the decoding and partitioning of the incoming data myself w/ the Streaming capability.

q2/ is this the right approach? and if it is...

q3/ --although this is not specifically related to Rocket-- can you recommend any 3rd-party crate(s) that do this and work well w/ Rocket?

thanks in advance + cheers;
rsn

[the10thWiz]

fail w/ 415 (Unsupported Media Type) presumably b/c Rocket doesn't recognize the multipart/mixed content-type header and consequently doesn't route the Request to the handler.

I believe it's actually failing b/c the Form data guard only supports multipart/form-data and application/x-www-form-urlencoded. If you cannot use one of these content types, you will need to use an external crate.

can you recommend any 3rd-party crate(s) that do this and work well w/ Rocket?

Not right now. It's a logical enhancement for my rocket-multipart crate though, so I'll look into adding the capability to parse multipart/mixed content.

[raif-s-naffah]

thanks Matthew for your prompt response. much appreciated!

FYI when implementing the parsing functionality in rocket-multipart, the standard in question also relies (or expects) incoming Parts to each expose their Headers so the implementation can check for the presence + contents of the following ones:

• content-type,
• content-length,
• custom headers --those named x-<something>.

may be something like multer's Field would be worth considering.

[the10thWiz]

Well, I've taken a stab at it (and released as v0.1.1). Let me know if there are any additional features that might be useful.

[raif-s-naffah]

thank you kindly Matthew!

i'll have a closer look at it tomorrow but quickly perusing the docs i noticed a method named contenty_type. was that intentional?

also, just to be sure, i should be able to wire this in my handler like so...

async fn put(mut data: MultipartReader<'_>) -> MyResponse { }

yes?

finally, if i find i have more questions, is it best to post them here or there?

thanks again + have a nice weekend.

[the10thWiz]

The content_type typo was not intentional. I'm going to fix that (I'll need to figure out what version I need to bump, but oh well).

also, just to be sure, i should be able to wire this in my handler like so...

If you look at the source file in the repo, I have a route (for testing) that's pretty much what you describe.

It's probably better to post questions to my git repos.

[raif-s-naffah]

hi Matthew,

couldn't resist the temptation and quickly tested your latest release and it works!

i'm marking this question as answered + will post followup questions relevant to this aspect on the rocket-multipart project.

thanks again for your response!